Silent Myocardial Infarction Among Young Sudden Cardiac Death Victims

Abstract Background Silent myocardial infarctions (SMIs) occur with atypical or no symptoms at all. The burden of SMIs among sudden cardiac death victims have recently been acknowledged. However, the prevalence of previously undetected SMI in young victims remains unclear. Purpose The aim of the present study was to determine the prevalence of autopsy verified SMI in SCD victims under 50 years old without a prior diagnosis of coronary artery disease (CAD). Methods Fingesture study consists of systematically collected consecutive victims of SCD in Northern Finland between years 1998–2017 (n=5,869). According to Finnish law, all unexpected deaths undergo medico-legal autopsy. The autopsies routinely included histological examinations, and a toxicology investigation was carried out if needed. The SMI was defined as focal scar detected by macroscopic evaluation of the dissected ventricles and histologic analysis of the myocardial samples with an absence of a history of previously diagnosed CAD. Pre-mortem clinical history was obtained from medical records, standardized questionnaire to the closest family members of the victims and police reports about the conditions of the death. Results Overall, 10.4% off all SCDs occurred among victims under the age of 50 years (610 victims). Most common underlying cause of SCD among young was CAD (44%). About 90% of the victims had no clinical diagnosis of CAD, however, 34% (78 victims) had previously undetected myocardial scar at autopsy indicating a previous SMI. The mean age of the young SMI victims was 44±4 and they were mostly men (87%). 24% of SCDs occurred during physical activity and 21% had SCD outdoors. The mean heart weight was 466±110 g and 67% had hypertrophied hearts. Three vessel disease was detected in 69% of the victims. Alcohol was detected in 17% of victims in toxicology investigations. Conclusions Previously undetected myocardial infarction is also common among young victims who experienced CAD associated SCD. Three vessel disease and cardiac hypertrophy were common autopsy findings among young SMI victims and about a fourth had SCD during physical activity. Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): Sigrid Juselius Foundation, Finnish Foundation for Cardiovascular Research